Dosage-dispensing devices find application in areas where in the course of one or more mixing- and/or treatment processes an end product is made out of a large number of different pulverous or granular ingredient materials. Examples which can be named for such processes include the chemical industry and also the pharmaceutical industry. While formulations at the development stage are mixed on a laboratory scale from minuscule quantities, the manufacture of the finished product consumes industrial-sized quantities of ingredient materials, because this is the only way to obtain a sufficient lot size and thus ensure an economical production. In particular in the pharmaceutical/chemical industry, the cleanliness of the instruments and utensils being used is of the foremost importance besides the purity of the ingredient products, because only through a strict quality management is it possible to maintain the quality standards which have meanwhile been established within a framework of certification systems in almost all branches of industry. In this environment, it is particularly important that the instruments involved are immediately after use subjected to an extremely stringent cleaning procedure, before the instruments can be put back into operation after they have undergone diverse cleanliness inspections and function checks. A particularly important aspect in the production of chemicals, particularly in the manufacture of pharmaceuticals, is the transfer of raw materials or intermediate products into intermediate holding-containers and/or mixing containers and, at the end of the production process, into transport containers and storage containers.
As a means to dispense defined quantities of formulation components even in large amounts with the highest possible accuracy, one uses metering elements with variable outlet apertures. Such metering elements can be arranged between the containers or also inside of tube conduits, so that the product flow can be controlled manually or automatically in conformance with requirements on the precision and speed of the dosage-dispensing process.
The problem with using a metering element in this manner is that during the filling- or dispensing process at least the inside of the element is in permanent contact with the product to be dispensed. This has the consequence that either a special metering element has to be used for each different substance to be dispensed, as a way to extend the usage intervals as much as possible, or that especially in view of the aforementioned quality standards the metering element is put through the cleaning and checking procedure after each dosage-dispensing process in order to prevent cross-contamination between different substances.
Added to this is the problem that during a certain time interval after the dosage-dispensing process has been completed and the receiving container has been removed, the user of the filling device can come into contact with the dosage substance. This is the case for example if there are product residues left over in the metering element and/or if a pulverous product with a tendency to spread dust is being dispensed. The possibility can therefore not be ruled out that the user may become contaminated through contact with the skin, the mucous membranes or airways, whereby the user's health could be endangered.
As a means to eliminate the last-mentioned aspect or to reduce the risks as much as possible, an emptying device for bags with an inner and outer bag (i.e. so-called bulk bags) is proposed in U.S. Pat. No. 5,944,070 to Schmidt, which includes a holder device for bulk bags and, arranged in central alignment below the holder device, a double-tube device with an inner and an outer tube. The latter device has a gripper device arranged preferably in the inner tube and movable in the up and down direction, which serves to hold the bag outlet of the inner bag and which can be pulled from the up to the down position by means of a pulling device that is operable from the outside.
A device to empty and fill flexible bulk material containers without causing contamination is described in US published application 2007/0251,599 to Denk. It uses a tubular film as connecting member from a container that is being emptied to a connector tube or an inlet opening. After the filling or emptying process has been completed, this tubular film is tied off together with the flexible container and/or the filled container, whereupon the contaminated film is detached and discarded.
These devices have a variety of disadvantages. Although in all devices an unintended escape of the filling material is prevented as far as possible and the risk of contaminating the environment and the user is thus reduced to a large extent, the filling material is in contact with the filling devices and/or metering elements during the transfer or filling process in all of the proposed arrangements. After using these kinds of devices in sensitive areas it will therefore be necessary to clean and/or decontaminate the entire filling- or dosage-dispensing apparatus. An appropriate cleaning involves a large amount of time and expense and necessitates a series of inspection checks before the filling- or dosage-dispensing device can be put back into operation.
In the present inventor's commonly-owned published application WO2008/017175 (Bohler '175), which is hereby incorporated by reference in its entirety, a dosage-dispensing device is proposed by means of which these drawbacks can largely be avoided. This dosage-dispensing device has a container for dosage material with an outlet spout that reaches into a metering element. The metering element has an inlet opening on the side that faces the container, a clamping profile and/or a quick-tightening device to releasably connect the outlet spout and the metering element, a slot-shaped outlet opening on the side that faces away from the container, a ring gap between the outlet spout and the inlet opening, a wall with an inside and an outside extending between the inlet opening and the outlet opening, and a supply of film material that is stored in the area of the outlet spout, in particular a plastic film or an elastomeric film. As a container, it is possible to use a reservoir hopper to which the outlet spout is solidly connected, for example welded. However, in addition it is also possible to attach the metering element to a container in the shape of a funnel configured for example in such a way that bags can be inserted into its fill spout, or which can be positioned under the outlet openings of large silos. It is further intended that the inlet opening, the inside of the wall and the slot-shaped outlet opening are covered with the film material.
However, with the foregoing arrangement it is possible that during a dosage-dispensing process pocket-shaped folds or wrinkles may appear in the film material during a dosage-dispensing process and that dosage material could be caught in these wrinkles. This could have the result that the outlet opening of the metering element can no longer be closed satisfactorily and will leak if one of these pockets forms in the slot-shaped outlet opening. Furthermore, this could also cause the destruction of the film material so that the latter would no longer perform its protective function.
It is therefore an object to provide a dosage-dispensing device that belongs to the aforementioned kind but provides the highest level of functional reliability and the best possible safety in regard to the risk of contaminating the environment.